Ultrasonic-assisted chemical etching of zinc-based alloy porous structures: Surface morphology evolution and mechanical property response

Additive manufactured zinc-based porous implants face the critical challenges of residual powder adhesion and high surface roughness, and traditional post-processing techniques are difficult to achieve uniform modification without sacrificing mechanical properties.This study employs a novel strategy of ultrasonic-assisted chemical etching (UACE), leveraging the synergistic effects of ultrasonic cavitation and chemical etching to achieve efficient removal of residual powder, surface homogenization, and preservation of mechanical properties, thereby effectively resolving the inherent conflict between surface quality and structural integrity. For Zn, Zn-0.5Mg and Zn-Mg-Cu porous structures, the optimized UACE process (10 % HCl+10 % HNO₃, 50 s) can remove Zn-Mg-Cu residual powders up to 40.38 %, and significantly reduce the surface roughness (Ra) from 10.37 µm to 5.43 µm for Zn-0.5Mg, and at the same time, the structural size and energy absorption capacity were retained up to 91.6 % and 76.1 %, respectively. This study not only provides a new paradigm for the precision post-processing of complex metal porous components, but also lays a key foundation for the clinical application of high-performance biodegradable zinc-based implants.